Integrated insulated and weatherproof roof system

ABSTRACT

AN INTEGRATED, INSULATED AND WEATHERPROOF ROOF SYSTEM HAS A BASE, A FIRST MONOLITHIC MASS, SUPPORTED BY THE BASE COMPOSED OF A LOW-DENSITY CONCRETE COMPOSITION AND A SECOND MONOLITHIC MASS ON A SURFACE OF THE FIRST MASS COMPOSED OF A BITUMINOUS MATERIAL THAT IS MECHANICALLY BONDED TO THE SURFACE OF THE FIRST MASS. THE ROOF SYSTEM IS FORMED FROM INITIALLY FLOWABLE MATERIALS BY FORMING ON A BASE A SLURRY CEMENT, EXPANDED BEADS OF A THERMOPLASTIC MATERIAL AND WATER, CURING THE SLURRY TO A SOLID MONOLITHIC MASS AND FORMING A LAYER OF A HOT BITUMINOUS MATERIAL ON A SURFACE OF THE SOLID MASS.

July 18, 1972 J. D. CARLSON 3,677,878

INTEGRATED INSULATED AND WEATHERPROOF ROOF SYSTEM Filed Feb. 2, 1971 2 Sheets-Sheet 1 PREPARE SLURRY OF CONCRETE COMPOSITION APPLY SLURRY TO BASE CURE SLURRY TO SOLID MASS PREPARE BITUMINOUS APPLY B'TUM'NOUS MATERIAL MATERIAL TO SOLID MASS INTEGRATED ROOF FIG. 3

I NVENTOR.

JOHN D. CARL SON MaJ/tWqI y 18, 1972 J. D. CARLSON 3,677,878

INTEGRATED INSULATED AND WEATHERPROOF ROOF SYSTEM Filed Feb. 2, 1971 2 Sheets-Sheet 2 United States Patent O1 hce US. Cl. 161-160 12 Claims ABSTRACT OF THE DISCLOSURE An integrated, insulated and weatherproof roof system has a base, a first monolithic mass, supported by the base composed of a low-density concrete composition and a second monolithic mass on a surface of the first mass composed of a bituminous material that is mechanically bonded to the surface of the first mass.

The roof system is formed from initially flowable materials by forming on a base a slurry cement, expanded beads of a thermoplastic material and water, curing the slurry to a solid monolithic mass and forming a layer of a hot bituminous material on a surface of the solid mass.

BACKGROUND OF THE INVENTION This invention relates to an integrated, insulated and weatherproof roof system made from initially flowable materials and to a method for making the same.

Conventionally, a built-up roof is formed of alternate layers of bituminous material and felt which are assembled or built-up in the field and applied over a subdeck. Such roofs consist of three to five plies of saturated felt that have been cemented or hot mopped together with bituminous materials on the sub-deck at a temperature of about 400 F. at which temperature the bituminous material has the high fluidity that is necessary for good penetration of the felt. The bituminous material is usually of a coal tar or asphalt origin. Conventionally gravel, slag or the like is embedded in the top layer of the bituminous material to protect the under layers of the roof from foot trafiic, sun and wind. These layers of saturated felt and bituminous material rest on a wood, metal or concrete sub-deck.

To make the concrete sub-deck, for example, a slurry made of, Portland cement, water and lightweight aggregate such as vermiculite or perlite is placed over a base and screeded to form an even surface. After the slurry has cured to a solid monolithic mass the alternate layers of hot bituminous material and felt are conventionally applied over the monolithic mass. This type of concrete sub-deck has several disadvantages. In preparing the slurry, about four gallons of water are needed for each cubic foot of solids in the slurry, and conse quently the slurry has a relatively high moisture content. Because of this high moisture content, the curing of the concrete requires six to seven weeks and, generally, the bituminous materials cannot be applied to the surface of the concrete mass for at least seven to eight days after it has been initially formed. Vents must be provided within the roof after the concrete mass has been covered with the bituminous materials so that the excess water contained in the concrete mass may be vented therefrom; and, the concrete mass requires a built-up roofing because the concrete mass itself is not weatherproof.

Also, vapor barriers such as a coating of a polyvinyl (alcohol) composition must be applied over the surface of the freshly formed concrete mass before the bituminous materials are applied thereto to protect the freshly formed mass from weathering such as rain which 3,677,878 Patented July 18, 1972 would wash out the cement in the freshly formed mass and to prevent a rapid evaporation of moisture from the surface of the concrete mass so that hydration of the cement may properly occur.

In accordance with the invention I have developed a novel roof deck assembly and a novel method for making the same from initially flowable materials which become solid enough within twenty-four or less hours for the application of a layer of bituminous material thereover. The need for vents, in the roof, the need for vapor barriers, and, quite surprisingly, the need for alternate layers of bituminous material and felt has been eliminated.

SUMMARY OF THE INVENTION An integrated insulated and weatherproof roof system comprises a first layer of a low-density concrete composition comprised of a homogeneous matrix of cement and of expanded beads of a thermoplastic material that are bonded to the cement and a second layer of a bituminous material that coextensively covers a surface of the concrete composition and that is mechanically bonded to the surface. The roof system is made by forming a slurry made of cement, expanded beads of a thermoplastic material and water as a first layer, curing the slurry to a solid monolithic mass and forming a bituminous material as a second layer on a surface of the solid concrete mass by heating the bituminous material to a temperature that disintegrates and displaces the ex panded thermoplastic heads at the surface of the solid concrete mass whereby the second layer of bituminous material becomes mechanically bonded to the surface of the solid concrete mass.

GENERAL DESCRIPTION OF THE DRAWING In the drawing:

FIG. 1 is a perspective view illustrating an embodiment of an integrated roof system made in accordance with the invention;

FIG. 2 is a cross sectional and greatly exaggerated view of the roof system of FIG. 1, taken at lines 11-11;

FIG. 3 is a flow diagram embodying the method for making the integrated roof system of FIG. 1 in accordance with the invention.

FIG. 4 is a perspective view illustrating another embodiment of an integrated roof system made in accordance with the invention.

DETAILED DESCRIPTION The roof system of FIG. 1 includes purlins 11, a base 13, a concrete monolithic mass 15, a bituminous monolithic mass 17 and a gravel layer 19. The monolithic concrete mass 15, as illustrated herein, includes reinforcing members 21 for increasing the strength of the monolithic concrete mass 15; however, reinforcing members are not a necessary part of this invention.

The purlins 11 are conventional structural members on top of a building that support the base 13. The base 13 may be composed of any suitable material such as wood, metal or the like.

In accordance with the invention the moonlithic concrete mass 15 in FIG. 1 is a layer of a homogeneous matrix of cement and of expanded beads of a thermoplastic material, preferably expanded polystyrene beads, that are uniformly dispersed throughout the matrix and bonded to the cement. A typical concrete mass made in accordance with the invention comprises /21 parts by Weight of an homogenizing agent, 3 parts by weight of expanded thermoplastic beads, and 50-90 parts by weight of hydrated portland cement. Such a typical mass has physical properties which are ideally suited for roof systems. Typical properties are given in the table below:

Properties Values Test method ASTM -272-53 The values in the table above for each property were determined in accordance with the standard methods of test as indicated.

Commercially available cements are useable in the practice of the invention such as, for example, conventional portland cements, gypsum products (such as plaster of paris), calcium-aluminate cements, high-alumina-cements, and magnesia cements or combinations thereof. Preferably, portland cement is used.

The expanded thermoplastic beads for use in the practice of this invention are commercially available. Preferably expanded beads of polystyrene are used and such beads are sold under the trademark, Dylite, and are made by Sinclair-Koppers Company. Such polystyrene beads are made from expandable styrene polymers and are expanded by heating the beads whereupon the blowing agent contained in the beads causes the beads to expand to the extent of to 30 times their original size. Thus, while the density of the unexpanded polystyrene beads originally are about that of water, the density of the expanded polystyrene heads is about one pound per cubic foot.

Because there is a great difference between the various ingredients of the concrete composition, particularly between the expanded polystyrene beads, cement and water, the ingredients tend to segregate and agglomerate when they are in the slurry form. Thus, a homogenizing agent such as the ones described in US. Pat. 3,272,765 or 3,214,393, have been developed to overcome the agglomeration and segregation of the expanded polystyrene beads in the slurry. The homogenizing agents help to dispose the expanded polystyrene beads uniformly throughout the slurry, maintain a uniform dispersion and provide for the bonding of the expanded polystyrene beads with the cement.

As will be apparent to those skilled in the art reinforcements or filters may be added to the concrete composition to meet various needs. For example, the concrete mass may contain nylon fibers, sisal and the like. The concrete mass 15 may also contain a variety of fillers and combinations thereof such as, for example, asbestos, wood fibers, chips shavings and dust, excelsior, cork, slag, fiber glass, hemp, jute, bagasse or the like. The use and the choice of fillers will depend upon the various needs.

In accordance with the embodiment of the invention illustrated in FIG. 1, the bituminous monolithic mass 17 is a layer of a bituminous material that coextensively covers the upper surface of the concrete mass 15. The bituminous material may be comprised of a rubber dissolved in a tar composition, asphaltic compositions, bituminous emulsions, mixtures of aromatic and coal tar pitch and the like. The bituminous layer 17 seals the concrete mass and permtis the concrete to develop its ultimate strength through complete hydration of the cement in the concrete mass 15. In service, the bituminous layer is capable of stretching and flowing as needed to seal minor cracks that may develop in the concrete mass from shifting in the building structure that may occur during the service life of the integrated assembly.

Bituminous materials are used in the practice of this invention because they have physical properties which are ideally suited for roof systems. Typical physical properties are given in the table below:

The values in the table above for each property were determined in accordance with the standard methods of test as indicated. Preferred bituminous materials for use in the practice of this invention are sold by Koppers Company, Inc. under the trade name Bitumen N0. 1 and Bitumen No. 2.

As illustrated in FIG. 2 the monolithic bituminous mass or layer 17 is superficially embedded in the upper surface of the monolithic concrete mass 15 and is mechanically bonded to the concrete mass 15 to form an integrated roof system. The bituminous material is yieldable and extensible. In a preferred composition the layer 17 can be stretched to about 10% of its original volume without failure of the layer by cracking. The layer 17 is locked with the concrete mass 15 and minor shifting or cracking of the concrete mass, while the roof system is in service, does not adversely affect the sealing quality of the bituminous material as it is capable of shifting along with the concrete mass without itself cracking or separating apart.

A conventional gravel layer 19 is used in the practice of this invention. The gravel layer 19 should be equal to the values established in Standard Test ASTM D-1863 for ultraviolet sun light resistance to protect the bituminous layer 17 from any degradation resulting from the sun light exposure.

Referring to FIG. 3 in the making of the integrated roof system of FIG. 1, a slurry of concrete composition is prepared, preferably of portland cement, expanded beads of polystyrene, a homogenizing agent and water. These constituents are added to a suitable blender preferably in accordance with the following formulation wherein parts are expressed as parts by weight:

The ingredients are thoroughly blended together in the blender, preferably by premixing the expanded beads of polystyrene and the homogenizing agent in the blender, then slowly adding water to this mixture and thoroughly agitating these ingredients until a homogeneous blend is achieved, and then slowly adding the portland cement to the blender and thoroughly mixing these ingredients to obtain a homogeneous slurry. The homogeneous slurry has a consistency such that it is readily flowable.

The slurry is then pumped to the roof by conventional pump and hose arrangement and is placed over the base 13 to a thickness of any desired dimension. Preferably, the slurry should be two inches in thickness. A temporary form has been previously secured on the base at its lateral edges to prevent the slurry from running off of the base. The slurry is then screeded to prepare an even top surface to receive the bituminous materials.

Within about twenty or less hours the slurry cures to a solid mass by hydration suificient to support foot traffic and the like. In the preferred roof system the bituminous material is poured over the solid concrete '15 to a preferred thickness of about /2 inch. Generally, the bituminous material is heated to a temperature of about 400 F. so that it has the proper viscosity for pouring onto the roof. When hot bituminous material comes into contact with the top surface of the solid concrete, the heat of the bituminous material melts and disintegrates those expanded polystyrene beads at the top surface of the solid mass but does not affect those expanded polystyrene beads below the top surface. The bituminous material fills the voids created by the disintegration. Consequently the bituminous material upon cooling is mechanically bonded to the concrete mass 15. This novel bonding mechanism insures the union of the bituminous material and the upper surface of the solid mass of lightweight concrete. Subsequently, gravel 19 or the like is placed over the layer of hot bituminous material.

A desirable feature of this invention is that the cement may be stoichiometrically balanced with the water in the slurry to contain the proper amount of water for hydration. Thus excess quantities of water need not be added to the slurry to achieve proper hydration of the cement. As is well known the less excess water added to the slurry in respect to the cement the greater the strength of the concrete. It is the water to cement ratio, not the cement content nor the granulometric composition, that determines to a large extent the strength of the concrete. Also, it is well known that the shrinkage or the reduction of volume of the concrete during curing is in proportion to the amount of cement paste in the concrete and the wateriness of this paste. It is believed that during the hydration of the cement the water between the gel particles of the cement evaporates, which causes the concrete to shrink, and also leaves extremely fine capillaries and air voids which may absorb water again on renewed humidification. Hence, shrinkage of the concrete and the formation of air voids in the concrete becomes less of a problem as the amount of excess water is reduced.

Another desirable feature of this invention is that the materials of which the roof system are composed are initially iiowable materials. Thus the materials may be prepared and conveniently pumped to the roof for their application in accordance with the invention. While the materials are initially flowable they harden to a solid, particularly the concrete composition, within a very short period of time such that they can sustain foot traffic and the like. Because the concrete composition cures to a hard solid in the short period of time the hot bituminous material can be applied to the surface of the concrete mass within about twenty-four hours or less. Advantageously, the early application of the bituminous material seals the concrete and prevents the formation of fine capillaries as previously described above.

Another desirable feature of this invention is that the concrete composition is self-insulated because of the homogeneous distribution of the expanded thermoplastic beads in the concrete. Consequently, the need for other insulation material are eliminated by my invention.

Another embodiment of the invention is shown in FIG.

4 which is similar to the embodiment of FIG. 1 except that a porous membrane or a layer of a reinforcing fabric 23 that is saturated with either an asphalt or tar-base material is disposed between the concrete mass 15 and the bituminous mass 17. The reinforcing fabric 23 reinforces the bituminous mass 17 (in a manner similar to the reinforcement of concrete with a steel mesh or reinforcing rods) so that the bituminous mass may withstand the stresses and strains from wind, vibration, and from the expansion and contraction of the bituminous mass itself. Typical reinforcing fabrics comprise cotton, or glass or jute-woven fabrics that are saturated with either an asphalt or tar-base material. The preferred fabric is cotton. Typical properties of reinforcing fabrics are:

Dry weight, oz./ sq. yd 1.24.5 Saturated weight, oz./sq. yd. 1.5-9.75 Breaking strength, p.s.i 40-75 Nominal thread count, threads per inch 9-32 In practice the reinforcing fabric 23 is placed over the concrete mass 15 within less than twenty-four hours after the concrete mass has been poured onto base 13. Subsequently, a layer of the hot, bituminous material is placed over the reinforcing fabric. The hot bituminous material will penetrate through the reinforcing fabric and, also, disintegrate the thermoplastic beads at the surface of the concrete mass 15 in the manner aforedescribed. After the bituminous material cools, the reinforcing fabric and the bituminous mass itself will be mechanically bonded to the concrete mass as aforedescribed. A layer of gravel may subsequently be disposed over the bituminous material.

In service, the reinforcing fabric will support the bituminous mass and prevent the cracking of the bituminous mass even though the concrete mass may develop a crack of up to A2 inch in size. The reinforcing fabric, particularly those made from cotton fibers, are extensible and will stretch with any movement in the concrete mass. A desirable feature of this embodiment is that the reinforcing fabric helps to dissipate the forces exerted on the bituminous mass over a larger area of the upper surface of the concrete mass.

What is claimed is:

1. An integrated, insulated and weatherproof roof system comprising:

(a) a base;

(b) a first layer of a low-density concrete composition that is supported by said base and that coextensively covers said base; said low-density concrete composition being a homogeneous matrix of cement and of expanded beads of a thermoplastic material that are bonded to said cement; and

(c) a second layer of a bituminous material that coextensively covers a surface of said concrete composition and that is mechanically bonded to said surface.

2. The integrated, insulated and weatherproof roof system of claim 1 further comprising a third layer of an aggregate material that coextensively covers said second layer of bituminous material.

3. The integrated insulated and weatherproof roof system of claim 1 including a reinforcing fabric disposed between said first and second layers.

4. The integrated, insulated and weatherproof roof system of claim 1 wherein said concrete composition comprises a mixture of about (a) /2-1 parts by weight of a homogenizing agent;

(b) 3 parts by weight of expanded beads of a thermoplastic material;

(c) 5090 parts by weight of portland cement;

said composition being formed by mixing said mixture with about 35-45 parts by weight of water to provide a slurry for application to said base.

5. An integrated, insulated and weatherproof roof system comprising:

(a) a base;

(b) a first monolthic mass comprised of a low-density concrete composition that is supported by said base and that coextensively covers said base; said first monolithic mass being characterized by the following physical properties:

Density, lbs/cu. ft. 33.0 Compressive strength, p.s.i 440 Moisture vapor transmission (permeance),

perms Thermal conductivity K value), B.t.u./hr./

sq. ft./ F./in. 0.7

(c) a second monolithic mass comprised of a bituminous material that coextensively covers a surface of said first mass and that is mechanically bonded to said surface of said first mass; said second monolithic mass being characterized by the following physical properties:

Specific gravity 0.99-1.34 Softening point, F. 129-220 Flash point, degrees 248-437 6. The integrated, insulated and weatherproof roof system of claim 5 including a reinforcing fabric disposed between said first and second masses; said reinforcing fabric being characterized by the following physical prop- 10. A method for making an integrated insulated and erties: weatherproof roof system comprising:

(a) forming a slurry comprised of cement, expanded Dry weight, oz./sq. yd 1.2-7.5 beads of a thermoplastic material and Water, as a Saturated weight, oz./sq. yd. lr9.75 5 first layer; Breaking strength, p.s.i 40-75 (b) curing said slurry to a solid monolithic mass; and Nominal thread Count, thrfiads P ind! (c) forming a bituminous material on a surface of said solid mass as a second layer by heating the bituminous material to a temperature that disintegrates and 10 displaces said expanded thermoplastic heads at the surface of said concrete mass. 11. The method of claim 10 including 7. A method for making a solid integrated, insulated and weatherproof roof system on a base from initially fiowable materials comprising:

(a) applying a slurry of cement, expanded beads of a thermoplastic material, and water as a first layer on applying an aggregate material on Said layer of hot said base; and tuminous material. after said slurry sets to a sohd mass, pp y a 12. The method of claim 10 including hot bitumiIlOllS material as a Second layer on a applying a reinforcing fabric over said solid mass beface of said mass at a temperature such as to disinfore applying said bituminous material. tegrate said expanded thermoplastic beads whereby said second layer of hot bituminous material be- Referemes Cited comes mechanically bonded to said surface of said UNITED STATES PATENTS mass- 3,104,196 9/1963 Shannon 161-208 The methdf1a 1m7lnclldmgi 3,345,246 10/1967 Sheahan 161-461 immediately after said second layer of hot bituminous 3,466,222 9 /1969 Curtis material has been pp pp y an aggregate 3,475,265 10/1969 Santry 16 5 material as a third layer on said second layer of said hot bituminous material. WILLIAM J. VAN BALEN, Primary Examiner 9. The method of claim 7 including applying a reinforcing fabric over said solid mass before applying said hot bituminous material. 15671; 161-160, 161, 162 

